Motor control system



M y 12. 1 3 I 4 G. E. KING 1,805,248

IOTOR CONTROL SYSTEM Filed Oct. 15, 1926 1:. Y I 1/ Series fi'ela' 2 Y 5h 1' 1- m fi /d ===-29 90 c" t I t L 1'" &

fi 1P 1 9a 1 I01 I20 cm- Sfroke INVENTCR George E. King ATTORNEY Patented May 12, 1931 UNITED STATES, PATENT OFFICE V GEORGE E. KING, OF WILKINSBUIR-G, PENNSYLVANIA, ASSIGNOB TO WESTINGHOUSE ELECTRIC 8: MANUFACTURING COMPANY, A CORPORATION OF PENNSYLVANIA MOTOR CONTROL SYSTEM Application-filed October 15, 1926. Serial No. 141,715.

My invention relates to motor-control systems and it has particular relation to thebraking of remote reversible motors such as those employed in planer systems and the like.

One object of my invention is to prov de an improved means for effecting dynamic braking of the motors automatically upon the failureof the source of power, when the motor is runningin either direction.

A secondobject of my invention is to provide means responsive to the counter-electromotive force of a reversible motor for automatically connecting the shunt field winding in a manner to provide effective dynamic braking when the motor is running in eithe direction. a 7

Another object of my invention is to pronamic braking for the motor when running in either direction.

A further object of my invention is the provision of a reliable means for stoppinga reversible motor quickly and independently of any external power.

- Another object of-my invention'is to rovide a system of the above-mentioned c aracter which shall be simple and reliable in operation and relatively inexpensive to manufacture and install.

ing an armature 1, a shunt field winding2 and a series field winding 3. The shunt field 'winding is connected between the line conductorsA and 5 through the cut and return resistors 6 and 7 and an auxiliary contactor 8. A main line contactor or switch 9 is adapted to connect the motor to the positive line conductor 4. Two pairs of reversing switches or contactors 10 and 12,11 and 13, respec tively, are connected to terminals of the armature, in accordance with a familiar practice.

The series field Winding 3 may be connected to the brushes ofthe armature 1 through the main-line contactor 9 and a series-field-circuit contacto-r 1 1. The series field Winding mayalso'be connected through the back contact members 140 of the series field contactor 14 in series relation with a braking resistor 15 and through the back contact members 90 of the main line contactor 9 to the pairs of reversing switches 10 and 12 or 11 and 13, across the brushes of the armature 1.

Pilot switches 17 and 18 are arranged in the bed of the planer motor and are me chanically operated at the beginning of the cut"and'.return stroke, respectively, of the planer, in a well known manner. Consequently, no further description or illustration thereof is deemed to be necessary. These switches thus serve to regulate the direction of rotation of the motor and, when closed, are connected to the line conductors 4 and 5 through the contact members of a low-voltagerelay 20, a suitable master switch 19, and.

either the back or lower contact members of 'thereversing switch 12 and the actuating coil 22a of the auxiliary contactor 22 to the conductor 5 or the back or lower contact members of the reversing switch 13 and the actuating coil 23a of the auxiliary contactor 23 to the conductor 5, de ending on which one of the pilot switches 1 or 18 is closed by the operation of the planer platen.

The resistors 6 and are connected in series relation with the shunt field winding 2 for regulating the speed of the motor, The cut resistor 6 is governed by a contactor or relay 24 that is actuated 7 a coil 24a to automatically provide a Mower cutting than returning speed for the planer motor. A full- ;field relay 16 is utilized to short circuit the cut and return resistors 6 and 7 when the motor is starting and stopping, the relay being actuated by a coil 16a connected in shunt relation to the starting and braking resistors 28 and 15. g

The shunt field relay 8 is connected between the positive line conductor 4 and the vactuating coils 9a and 14a of the line contactor 9 and the series field contactor 14, re-

spectively, to the line conductor 5; The starting switch 21 is connected, inparallelcircuit relation, to contact members of the low-voltage reIay20. The stop switch 26 is connected between line conductors 4 and 5 by a circuit extending either from conductor 4, through start switch 21, stop switch 26, actuating coil 20a of low-voltage relay 20', to the line conductor 5, or from line conductor 4, through the contact members of low-voltage relay '20, resistor 27, the stop switch 26, actuating coil 20a of low voltage relay 20, to the line conductor 5.

The master switch 19 is connected between the line conductors 4 and 5 through the cut. pilot switch 17, back contact members on the reversing switch 12 and through the actuating coil 22a of the auxiliary relay 22, or

through the return pilot switch 18, back contact members of the reversing switch 13 and through the actuating coil 23a of the auxiliary relay 23.

The actuating coils of the reversing switches 10 and 12 and 11 and 13 are connectd between the motor side of the seriesfield-circuit contactor 14 and the negative line conductor 5 through interlocks on the auxiliary relays 22 and 23, respectively;

Holding circuits are provided for t e reversing switches 10 and '12 and 11 and 13, and are controlled by interlocks on the said switches that are connected in series relation with their actuating coils 10a and 12a and 11a and 13a, respectively, to short circuit the contact members of the auxiliary'relays 22 and 23 when the reversing switches 10 and l2 and 11 and 13, respectively, are closed.

The operation of the system shown in the drawing may be described as follows Assuming that the pilot switch 17 is closed foreffecting a cutting stroke and that the starting switch 21 and the master switch 19 have been closed, a circuit is established from the positive line conductor 4 through the starting and stopping switches 21 and 26, the actuating coil 20a of the low-voltage relay 20 to the 1 negative line conductor 5. Upon the closure of the lowvolta e relay 20, the actuating coil 8a of the shunteld relay 8 will be energized, causing the relay 8 to be actuated to close a circuit through the upper: contacts of the refrom the lay and through the'shunt field winding 2. The closure of the low-voltage relay 20 also completes a circuit from the positive line conductor 4 through the master switch 19, the pilot switch 17, the back contact members of the reversing switch 12 and the actuating coil 22a of the auxiliary relay 22 to the negative line conductor 5, causing the relay 22 to operate to close its contacts.

Upon the'operation of the auxiliary relay 22 and the consequent closing of the contact members of this relay, a circuit is established from the positive line conductor 4, through the low-voltage relay 20, the lower contact member of the auxiliary relay 22, the actuating coil 9a of the main line contactor 9 and the actuating coil 14a of the series-field-cirtor 5. Closing of the contact members of the low-voltage relay 20 also established a holding circuit for the actuating coil 20a, through contact members of relay 20, resistor 27, stop push-button switch 26, and the actuating coil 20a, to the negative line conductor 5. The'circuit connections above discussed and others hereinafter more particularly specified are thus established in the proper se uence, regardless of theposition of the start button switch 21. y

The closure of the auxiliary relay 22, the main-line contactor 9 and the series-field-circuit contactor 14 causes a circuit to be established from positive line conductor 4, through the main-line switch 9, the series field winding-.3, series-field-circuit contactor 14, the upper contact member of auxiliary relay 22, the actuating coils 13a and 11a of the reversing switches 13 and 11, respectively, to the negative line conductor 5. The closure of the reversing contactors 13 and 11 connects the armature winding 1 across the line conductors 4 and 5 for operation in the cutting direction. The circuit for the motor may be traced from the negative line conductor 4, through the upper contact members of main-line contactor 9, series field 3, upper contact members of series-field-circuit contactor 14, the uppermost contact members of reversing switch 13, the motor armature 1, the uppermost contact member of reversing switch 11, and starting resistor 28, to the negative line conductor 5.

Actuation of the auxiliary relay 22, in addition to establishing circuits for the reverspushing switches 13 and 11, establishes a circuit positive line conductor 4, through the upper contact members of contactors 9 and 14, the upper contact member of auxiliary relay 22, the actuating coil 24a of the cuttingspeed regulatingrelay 24, to the negative line conductor 5. The speed of the motor in the cut direction will thus be slow, as desired, since a material portion of the resistor sections 6 and 7 is shunted by the operation of the cutting-speed regulating relay 24.

When the motor armature is first supplied 1' connecte braking resistor 15 and the starting resistor with energy, as above-explained, the starting resistor 28 is connected in series-circuit'relation to the armature; however, this startin resistor is rovided with a shunting switcfi 29. This sliunting switch is controlled by an actuating coil 29a soconnected with reference to the motor armature as to be responsive to a predetermined counter-electromotive-force of the motor. Since the counter-electromet-ive-force is a direct function of speed, the elements 29 and 29a function as an accelerating relay to shunt the starting resistor 28.

A full-field relay 16 is arranged to close a circuit in shunt relation to the resistors 6 and 7 when the motor is stopping or reversing, thereby permitting a larger current to flow through the shunt field winding 2. This rela is actuated by'a coil 16a which is in parallel circuit relation to the 28. This causes the full-field relay 16 to close when current is flowing through either the starting resistor '28, while starting, or the A braking resistor 15, when the motor is stopping. J

Upon closure of the interlock on the reversmg switch 13, the actuating coils 13a and 11a are connected across the annature 1 through the reversing switches 13 and 11, providing a holding circuit for maintaining said switches closed by means of the counterelectromotive force during dynamic braking at the end of the cutting stroke, as traced below.

At the end of the cuttingstroke, the out pilot switch 17 is actuated to the open posi-' tion and the return pilot switch 18 is actuated to the closed position in the usual manner. During the transition period between the opening of the cutting pilot switch 17 and the closing of the return pilot switch 18, the actuating coil 22a of the auxiliary relay 22 will be deenergized, causing said contactor to open, thereby interrupting the energizing circuit to the actuating coils 9a and 14a of the main line contactor 9 and the series-field-circuit contactor 14, causing the latter two contactors to also 0 n. The back contact members and o the main line contactor 9 and the series-field-circnit contactor 14 are thus closed by means of their corresponding actuating coils. 9b and 14b that are connected across the terminals of the armature 1, thereby setting up a dynamie-brakingcircuit through the braking resistor 15 and the seriesfield winding 3.

The dynamic-braking circuit comprises the armature 1, the uppermost contact members of reversing switc 13, the back or lower contact members 90 of main line contactor 9, the

series field 3, the back contact members 140 of the series-field contactor 14, the dynamicbrakin resistor 15, the upper contact members o the reversing switch 11 to the armature 1 of the motor.

13 and 11 are held closed by reason of the counter-electromotive-force of the motor being applied to their actuating coils through the previously traced circuit. When the counter-electromotive-force of the motor drops substantially to zero, the reversing switches 13 and 11 open. In the meantime, the transition has taken place and the return pilot switch 18 is closed, whereupon actuating coil 23a is energized and the auxiliary relay 23 closes its contact members. Operation of the relay 23 causes operation of the main line contactor 9 and the series-field contactor 14, whereupon a circuit is established for the respective actuating coils 10a and 12a of the reversing switches 10 and 12. This circuit may be traced through the contact members of contactors 9 and 14 and the upper contact members of auxiliary vrelay 23, actuating coils 10a and 124, respectively, to the negative line conductor 5.

The connections of the series field winding 3 are, however, reversed with respect to the armature 1, so that when the direction of current flow through the armature reverses, the direction of current flow through the field winding 3 remains in the same direction. It will be noted that, during the return stroke, neither the relay 16 nopthe relay 24 is energized. Substantiall all sections of the resistors 6 and 7 are t us in circuit with the shunt field winding insuring'a Weak excitation and, in consequence, a rapid returnspeed.

At the end of the return stroke, the return pilot switch 18 is opened, and the cutting pilot switch 17 is actuated to the 7 closed position. During this transition period, thecontactors 9 and 14 open them upper contact members and close their lower contact members; the contact members of the pressed, the low-voltage relay 20 is deenergized, which deenergizes the actuating coils of the main-line contactor 9, the series-fieldcircuit contactor 14 and the actuating coil of the shunt-field relay 8, causing these contactors to open. On the opening of the shunt field relay 8, it closes a circuit through its back contact members 8b connecting the shunt field winding 3 across the armature of the motor, and is held in this position by the actuating coil 80" which is connected across the armatures to the motor and is therefore energized in accordance with the countervoltage of the motor. Since the shunt field winding is connected: across the armature of the motor, the current in the shunt field winding will vary as the counter-voltage varies to aid in establishing a dynamic-braking circuit similar to the previously traced'circuits on interruption of the power to the armature alone, when reversing.

It will be seen that I have provided a relatively simple system whereby electric braking is utilized when a reversible motor is reversing in either direction, and also means for utilizing the shunt field winding to aid such braking upon failure of thefsourceof power. 1

It will be understood that I do not limit my invention to the specific form shown or ing, a series field winding and a shunt field winding, a braking resistor, a source of power, means for connecting said motor windings to said source, means rendered active u on failure of said power for connecting said shunt field winding across the armature winding, and means for connecting said braking resistor and said series field winding in series relation with the armature winding in a manner to aid .the shunt field winding to provide automatic electric braking when the motor is running in either direction. ,7

2. In a motor-control system, in combination, a motor provided with shunt field, series. field and armature windings, a variable resistor disposed in sef'ies-circuit relation with said shunt field winding, a startin resistor, a

source ofpower supply, means isposed to connect said shunt field winding and variable resistor across said power supply, means controlled by said shunt field power-supply connecting means for connecting and disconnecting said armature and series field windings from said source of power, and means operable; in response .to the failure of said power supply for said-motor to connect said shunt field winding, variable resistor and startingture, shunt and series field windings, a shunt resistor across the motor armature. Y

'3. In a motor-control system, in combination, a motor provided-with ashunt field, se-

ries field and armaturewindings, a variable resistor disposed in'seiies relationwith suid shunt field winding, a startingresistolf, a

source of power supply, means dispose d to G5 connect said shunt field win'dingand variable resistor across said power supply, means conwinding, variable resistor and starting resistor across the motor armature to excite the shunt field by the counter-electromotive force of the motor, a braking resistor, and means disposed to reverse and connect said series field winding and braking resistor in circuit with said motor armature to effect dynamicbraking action by the motor.

' 4. In a motor-control system, in combination, a motor provided with a shunt field, series field and armature windings, a variable resistor disposed in series relation with Y said shunt field winding, a starting resistor, a source 'of power supply, means dlsposed to connect said shunt field windin and variable resistor across said power supp y, means controlled by said shunt field power-supply connecting means for connecting and disconnecting said armature and series field windings from said source of power, means operable in response to the failure of said power supply for'said motor to connect said shunt field winding, variable resistor and starting resistor'across the motor armature to excite the shunt field by the counter-electromotive force of the motor, a braking resistor, means disposed to reverse and connect said series field winding and braking resistor in circuit with said motor armature to effect dynamicbraking action by the motor, and means responsive to the voltage drop across said brak; ing resistor for shunting said variable resistor.

'5. A motor having armature, series and shunt field windings, an accelerating resistor disposed for connection in circuit with said armature, a source of power for said motor, means for connecting said shunt field winding across the source of power, means for connecting and disconnectingvsaid armature and series field windings in series-circuit relation from said source of power, dynamicbraking means for said motor, and means res onsive to failure of said source of-power dis osed to connect said shunt field winding an accelerating resistor in series-circuit relation across the armature winding whereby the efl'ect of the dynamic-braking means is aifected by said shunt field windings.

6. In combination, a motor having armafield resistor, a braking resistor, a source of power I supply, means for connecting said shunt field winding and said field resistor in series-circuit relation across said source of ower supply, means for reversing said series ture winding, means-responsive to failure of eld winding, means for reversing said arma- 9 posed in circuit relatlon with said shunt field said source of power supply disposed to actuate saidv series-field-winding-reversing means and said shunt-field-winding-connecting means to therebyconnect said series field winding and braking resistor in series-circuit relation across said armature winding, and

' to connect said shunt field winding and field shunt-field-win resistor across said armature winding whereby said shunt and series field windings cooperate to establish compound field excitation for effecting dynamic braking by said motor, and means responsive to the current in said braking resistor for shunting said ing resistor.

7. In a motor-control system, in combination, a motor (provided with series field and armature win ings, reversing means for said series field winding, reversin means for said armature winding disposed or operation by said field-winding-reversing means, a source of power supply, means disposed to actuate said series-field-winding-reversing means to a position to effect motor operation, and means controlledbysaid series-field-winding-reversingmeans for actuating said armature-reversaing means to a position to connect said motor armature winding in series-circuit relation with said series field winding across said source of power supply in response to the actuation of said field-winding-reversing means to its position effecting motor operation, said armature-reversing means being connected across .said armature winding to be responsive to the counter-voltage of said armature when the power supply is disconnected from the motor.

8. In a motor-control system, in combination, a motor having armature, serles and shunt field windings, a variable resistor diswinding, a source of power supply, means for connecting said shunt field winding and variable resistor across said source of power supply, means responsive to failure of said power supply for connecting said shunt field windin across said armature winding, means or connecting said armature winding and series field winding across said power.

supply for effecting motor operation, a braking resistor, and means controlled by said power-supply failure means for connecting said braking resistor across said armature winding to establish dynamic-braking action by said motor.

9. In a motor-control system, in combination, a motor having armature," series and shunt field windings, a variable resistor disposed in circuit relation with said shunt field winding, a source of power supply, means for 7 connecting said shunt field winding and variable resistor across said source of power sup- 7 ply, means responsive to failure of said power supply for connecting said shunt field winding across said armature winding, means for connecting said armature winding and series field winding across said power supply for effecting motor operation, a braking reslstor,

means controlled by said power-supply failure means for connecting said bra ing resistor across said armature winding to establish dynamic braking action by said motor,

and means responsive to current in said braking resistor for shunting said variableresistor to thereby increase said braking action.

10. In a motor-control system, in combination, a motor having armature, series and shunt field windings, avariable resistor dising resistor, and means controlled by said power-supply-failure means for reversing said series field winding and connecting it in series relation with said raking resistor across said armature winding, whereb dynamic-braking action resulting from sald series and shunt field windings is rendered accumulative.

11. In a motor-control system, in combination, a motor having armature, series and shunt field windings, a variable resistor disposed in' circuit relation with said shunt field I winding, a source of power supply, means for connecting said shunt field wi ing and variable resistor across saldsource of power supply, means responslve to failure of mud power supply for connecting said shunt field wlnding across said armature winding,means for connecting said armature winding and series field winding across said power supply for effecting motor operation, a braking resistor, means controlled by said power-supply-failure means for reversing said series field winding and connecting it in series relation with said braking resistor acrosssaid armature winding, whereby d namic-braking action resulting from sai series and shunt field windings is rendered accumulative, and means responsive to current in said brakin resistor for shunting said variable shunteld-winding resistor to thereby increase said braking action.

12. In a motor-control system, in combination, a motor rovided with armature, series and shunt eld windin s, a resistor disposed in'circuit relation wit said field winding, a source'of power'supply, means for conmeeting said resistor and shunt field winding across said. source of power supply, means for connecting said series field winding 1n series-circuit relat1on across said source of power, means for reversmg said armature winding, a braking resistor, means for dissaid braking 7 source of power supply,

connecting said series field and armature windings from said source of power before said armature winding is reversed, and means controlled by said power-disconnecting means for reversing 'saidseries field winding and connecting it in series-circuit relation with resistor across said armature winding to establish dynamic-braking action by the motor.

13. In a motor-control system, in combination, a motor rovided with armature, series and shunt field windings, a resistor disposed in circuit relation with said field winding, a means for connecting said resistor and shunt field winding across said source of power supply; means or connecting said series field winding in series-circuit relation across" said source of power, means for reversing said armature winding, a braking resistor, means for disconnecting said series field and armature windings from said source of power before said armature windin is reversed, means controlled by said powerisconnecting means" for reversing said series field winding and connecting it in series-circuit relation with said braking resistor across. said armature lish dynamic-braking action by t motor, and means responsive to the counter-Volta .of said armature winding for rendering said means mefiective to re-- armature-rev verse said armature until the counter-voltage has decreasedto a predetermined value.

14. In a motor-control-system, in combination, a motor provided with armature, se-

. ries and shunt field windings, a resistor disposed in'circuit relation with said field winding, a sourceof power supp means for conmeeting said resistor and s unt field winding across said source of power supply means for connecting said series field win in series-circuit relation across said source of actionb the motor,

vtion, a motor power, means for reversing said armature wmdlng, a brakmg resistor, means for disconnecting said series field and armature windings from said" source of power before said armature winding is reversed, means controlled by "said ower-disconnecting means for reversing sai series field winding and connectin it in series-circuit relation with said braking resistor across said armature winding to establish dynamic-braking and means responsive to current 1n said braking resistor for shunti said shunt-field winding resistor to further increase said dynamic-braking action.

a 15. In a motor-control system, in combinagrovided with armature, series and shunt fiel windings, a resistor disposed in circuit relation with said shunt field winding,'a source of power sup ly, means for connect-ing said resistor and s unt field winding across said source of power supply, means for connecting said series field wind-ingdn series-circuit relation across said source of windin to estab-v windings from said source of means for diswinding, a braking resistor d and armature connecting said series fiel windings from said source of power before said armature winding is reversed, means controlled by said power-disconnecting means for reversing said series field winding and connecting it in series-circuit relation with said braking resistor across said armature winding to establish dynamic-braking action by the motor, and means responsive to failure of said power source for connecting said shunt field winding and shunt-field-winding resistor in series-circuit relation across said motor armature, said means being disposed, upon failure of power supply, to reverse said series field winding and to connect it in seriescircuit relation with said braking resistor across said armature winding.

16. In a motor-control system, in combination, a motor provided with armature, series and shunt field windings, a resistor dis osed in circuit relation with said field windlng, a

source of power supply, means for connecting said resistor and shunt field winding across said source of power supply, means for said armature and serles field connectin wmdmgs 1n ser1es-c1rcu1t relatlon across sa1d source of power, means for reversing said arsaid braking resistor across said armature winding to establish dynamic-braking action by the motor, means responsive to failure of said power source for connecting said shunt field winding andshunt 'field resistor in series-circuit relation across said motor arma-' lob ture, said means being disposed, upon failure of power supply, to reverse said series field winding and to connect 1t 1n series-clr- 'cuit relation withsaid braking resistor across said armature winding, and means responsive to current in said brakin resistor forshunting said shunt-field win ing resistor to further increase said dynamic-braking action.

,f 17. :In a motor-control system, incombination, a motor provided with armature, series and shunt field windings, a resistor disposed ng in circuit relation with said field windlng, a

source of power supply, means for connecting sa d resistor and shunt field winding across said source of power supply, means or connectingsaid armaturev and series field windmgs in series-circuit relation across said source of power, means for reversing said-ar mature winding, a braking resistor means for disconnecting saidseries field and armature power before said armature winding is reversed. and means controlled by said power-disconnecting means for reversing said series field winding and connectin it in series-circuit relation with said braking resistor across said armature winding to establish dynamic-braking action by the motor.

18. A system of motor control com rising a reversible motor having a shunt fiel winding and an armature wlnding, a source of power, means for connectlng sa1d armature W1I1d1l1g't0 the source of power, means for ,connecting the field winding to the source of power, a dynamic braking circuit for the motor, and means rendered active upon failure' of the voltage of the source of power and responsive to the counter-electromotive force of said reversible motor for connecting the dynamic braking circuit in series with the motor and for connecting the shunt field winding to the armature winding in a dirw tion to provide strong field excitation while the dynamic braking circuit is connected to the motor.

19. A system of motor a reversible motor having an armature winding, a shunt field winding and a series field winding, a source of power, means for connecting said motor windings to said source, a dynamic braking circuit for said motor, means for e'stablishin the dynamic braking circuit for the motor upon failure of voltage of the source of supply, means rendered active I upon failure of voltage of the source of power for disconnecting the shunt field winding from said source and for so connecting it across the armature winding that the counter-electromotive force of the motor tends to increase the field strength during dynamic braking irrespective of the direction of rotation of the motor, and means for so connecting the series field winding in said circuit that it aids the shunt field winding irrespective of the direction of rotation of said motor.

In testimony whereof, I have hereunto subscribed my name this 2nd day of October,

GEORGE .E. KING.

control comprising 

